Both observational and proxy records of climate change often show quasi periodic variations similar to solar activity cycles over a wide range of time scales. However, the detailed mechanism and the extent of the influence of solar activity on climate change have not been clearly understood. Although the exact role of each of solar parameters on climate change has not been quantitatively clarified, several possible mechanisms are proposed; such as the forcing through total (e.g. Lean et al., 1995) and spectral irradiance (e.g. Haigh 1996; Kodera and Kuroda, 2005), solar wind (e.g. Tinsley, 1996) and the galactic cosmic rays (Friis-Christensen and Svensmark, 1997; Svensmark, 2007). Among these parameters related to solar activity, galactic cosmic rays possess characteristic variations depending on the polarity of solar dipole magnetic filed as shown in Figure 1.

The polarity of solar dipole magnetic field reverses at every maxima of 11-year sunspot activity cycle, and so…